Methods for drying a surface of a disc-shaped article are typically used in semiconductor industry for cleaning silicon wafer during production processes (e.g. pre photo clean, post CMP-cleaning, and post plasma cleaning). However, such a drying method may be applied for other platelike articles such as compact discs, photo masks, reticles, magnetic discs or flat panel displays. When used in semiconductor industry it may also be applied for glass substrates (e.g. in silicon-on-insulator processes), III-V substrates (e.g. GaAs) or any other substrate or carrier used for producing integrated circuits.
Several drying methods are known in semiconductor industry. Many drying methods use a defined liquid/gas boundary layer. Such drying methods are better known as Marangoni drying methods.
U.S. Pat. No. 5,882,433 discloses a combined Marangoni spin drying method. Thereby deionised water is dispensed onto a wafer and simultaneously a mixture of nitrogen with 2-propanol is dispensed. The 2-propanol in the nitrogen shall influence the liquid/gas boundary layer in that a surface gradient shall occur, which leads to the effect that the water runs of the wafer without leaving any droplets on the wafer (Marangoni Effect). The gas dispenser directly follows the liquid dispenser while the liquid dispenser is moved from the centre to the edge of the wafer and while the wafer is spun and thereby gas directly displaces the liquid from the wafer. Alternatively U.S. Pat. No. 5,882,433 discloses a method where an aqueous solution is removed by an organic solution.
The latter has the problem that an increase of defects occurred when drying a wafer. However, the increase of watermarks did not always occur but the negative effect increased when switching from 200 mm technology to 300 mm.
It is therefore an object of the invention to avoid the occurrence of watermarks when drying and simultaneously making the drying process easier to control.